Underground electrical wiring help


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Old 07-24-16, 12:39 PM
J
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Underground electrical wiring help

I am reinstalling underground PVC conduit. The previous install had moisture in the conduit and water would seep into the connectors and T's and cause the GFI to trip.

I reinstalled this past week and made sure all connections were sealed perfectly. The system works fine now.

To my horror, I read yesterday, that all PVC underground conduit will condense moisture and I will probably have the same problem again.

I also read: (1) all connections where there are electrical wires connected together must be at the highest point or water will seep into the wire and trip the GFI. (2) You can drill a hole in the bottom of the PVC, at the low end, and the water will drain there avoiding the problem.

Is this true and will drilling the hole solve the problem?

My only other choice is to pull out everything I just did; run the wire and conduit to a shed and run wire and conduit from the shed to the electrical boxes and make sure all actual connections are at a high point.

Any suggestions will be appreciated.
Thanks,
Jack
 
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Old 07-24-16, 12:51 PM
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The thing is conduit underground is considered a wet location by NEC. Wire used underground needs to be rated for wet locations and any splices underground should be in an access box and have an approved splice for wet areas. It's best to run continuous piece of wire with no splices underground. Water will eventually collect in the conduit from condensation. I would not drill holes in the conduit that could end up being a bigger problem by letting more water in.
 
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Old 07-24-16, 12:58 PM
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Since the conduit is underground..... anything above ground is higher. Any junction box above ground will be above any water line.

Don't drill a hole in any underground conduit. That would allow the pipe to fill with water.
 
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Old 07-24-16, 01:04 PM
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A small hole can be drilled in the bottom of the receptacle box to allow water to drain out.
 
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Old 07-24-16, 01:10 PM
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A small hole can be drilled in the bottom of the receptacle box to allow water to drain out.
Good point!

I drill a hole in every weatherproof box I install. A 1/8'' or 3/16" is all that's needed.
I also use silicone on the threads of any top of the box screw in blank plugs.
I also silicone only the top edge between any device and box.
 
 

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